Newborn thyroid problem. In newborns?

Hello doctor, I gave birth to a new born baby girl which is 10 days old. I had C-section and she was born on 37.3 weeks. She was born early because my amniotic fluid was a bit high. When she borned i saw her eyes and they were yellow. I consulted a child specialist and she said to check her billrubin level to confirm whether she has jaundice or not. The level of total billrubin was high at 15.4mg/dL and of direct billrubin was 0.9 mg/dl.The doctor said to have a phototherapy to reduce her billrubin level. She had phototherapy day before yeaterday and her level reduced to 8.3 mg/dl She said about a TSH and T4 test about thyroid. The level of TSH is 11.59 micro IU/ml The level of T4 is 113.52 nmol/L Doctor i am very much worried... will my baby be able to live a normal life? Is there any treatment for this problem? We dont have any thyroid history in family nor i have thyroid. What is the cause of thyroid in newborns??? Please help me out!!!